package com.example.nio;

import org.springframework.util.StringUtils;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Iterator;

/**
 * TODO: 这里要写注释的!
 */
public class MultiplexerTimeServer implements Runnable {
    private Selector selector;
    private ServerSocketChannel serverChannel;
    private volatile boolean stop;

    public MultiplexerTimeServer(int port){
        try {
            selector= Selector.open();
            serverChannel= ServerSocketChannel.open();
            serverChannel.configureBlocking(false);
            serverChannel.socket().bind(new InetSocketAddress(port), 1024);
            serverChannel.register(selector, SelectionKey.OP_ACCEPT);
            System.out.println("the time server is start in port: " + port);
        }catch (Exception e){
            e.printStackTrace();
            System.exit(1);
        }
    }

    public void stop(){
        this.stop= true;
    }

    @Override public void run() {
        while (!stop){
            try{
                selector.select(1000);
                Iterator<SelectionKey> it= selector.selectedKeys().iterator();
                SelectionKey key= null;
                while (it.hasNext()){
                    key= it.next();
                    it.remove();
                    try {
                        handleInput(key);
                    }catch (Exception e){
                        if(key!=null){
                            key.cancel();
                            if(key.channel()!=null){
                                key.channel().close();
                            }
                        }
                    }
                }
            }catch (Throwable e){
                e.printStackTrace();
            }
        }
        if(selector!=null){
            try{
                selector.close();
            }catch (Exception e){
                e.printStackTrace();
            }
        }
    }

    private void handleInput(SelectionKey key) throws IOException {
        if(key.isValid()){
            if(key.isAcceptable()) {
                ServerSocketChannel ssc= (ServerSocketChannel) key.channel();
                SocketChannel sc= ssc.accept();
                sc.configureBlocking(false);
                sc.register(selector,SelectionKey.OP_READ);
            }
            if(key.isReadable()){
                SocketChannel sc= (SocketChannel) key.channel();
                ByteBuffer readBuffer= ByteBuffer.allocate(1024);
                int readBytes= sc.read(readBuffer);
                if(readBytes>0){
                    readBuffer.flip();
                    byte[] bytes= new byte[readBuffer.remaining()];
                    readBuffer.get(bytes);
                    String body= new String(bytes,"UTF-8");
                    System.out.println("the server receive order: "+body);
                    String currentTime= "query time order".equalsIgnoreCase(body)?new SimpleDateFormat("yyyy-MM-dd hh:mm:ss").format(new Date()):"bad order";
                    doWrite(sc,currentTime);
                }else if(readBytes<0) {
                    key.cancel();
                    sc.close();
                }
            }
        }
    }

    private void doWrite(SocketChannel channel,String response) throws IOException {
        if(!StringUtils.isEmpty(response)){
            byte[] bytes= response.getBytes();
            ByteBuffer writeBuffer= ByteBuffer.allocate(bytes.length);
            writeBuffer.put(bytes);
            writeBuffer.flip();
            channel.write(writeBuffer);
        }
    }
}
